This invention relates to the field of electrical relays and more particularly, is related to a single-cycle magnetic relay in an electrical interlock system which must be manually set prior to each operation.
It is well known to provide electrical interlocks in systems to prevent operation unless specific conditions have been met. For example, as a safety measure in automobiles, the ignition system may be disabled until the driver and all of his passeners have fastened their seat belts. To implement such a system, an electrical interlock operated by sensors or switches sequentially set by the driver and passengers entering the car and fastening the belts may be provided in the ignition system of the automobile. Unless the belts are fastened after entry, the interlock disables the ignition system and the engine cannot be started.
It will be recognized that a failure of the electrical interlock system may completely disable the ignition system and prevent operation of the automobile. Such a situation may not only be frustrating to the driver and his passengers but also could prove to be a serious hazard particularly in an emergency situation in which the automobile must be moved.
To remedy the situation and eliminate the possible hazards posed by the electrical interlock, an override or bypass relay has been installed to bypass the electrical interlock. The relay should be of the type that requires manual resetting before each override operation and located in a position not readily accessible to the driver. Current designs of bypass relays have been successful but there is always a desire to have a relay and system that is more reliable and inexpensive.
Accordingly, it is an object of the present invention to disclose a highly reliable manually set magnetic relay which automatically disables itself when deenergized to limit its use to a single-cycle or one-time operation. It is a further object to disclose a device which includes a bypass relay function along with an electrical interlock relay function. It is yet another object to disclose a relay which is of simple, rugged and economical construction. Other objects and features will be in part apparent and in part pointed out hereinafter.
The present invention resides in a manually settable magnetic bypass relay which includes two sets of contacts which perform two separate functions.
The magnetic relay comprises a set of normally closed contacts which act as the load switch for the electrical interlock, a set of normally open contacts which when closed act as the bypass, a cantilevered flexible clapper arm and latch spring which move in response to an electromotive force and on which one of the normally closed contacts is positioned, a manually operable actuator which closes the set of normally open contacts, and an electromagnetic coil which is serially connected electrically to the interlock logic module. If a sequence of events occurs in a predetermined proper order, i.e. the fastening of the seat belt after a person is seated in the car, no signal is sent from an interlock logic module to open the load switch and therefore cut off the power from the starter motor. However, if the sequence occurs in the wrong order the interlock logic module sends a signal to energize the coil upon attempting to start the car which causes the clapper arm and latch spring to move in response to the electromotive force and open the normally closed interlock load contacts so the car can not be started.
The bypass system of this relay can override the load switch of the electrical interlock when the load switch is in the open contacts position by providing a parallel circuit which can be manually actuated. The manual pressing of the actuator closes the normally open bypass contacts and completes the circuit. Subsequent energization of the coil when starting the car causes the clapper and, in turn, bypass contacts to move from a first latch position to a second latch position so that upon deenergization of the coil the contacts separate and go back to the normally open position.